A series of 3DOM Cu-Ce catalysts for CO-SCR were prepared by a colloidal template method. Among these catalysts, 3DOM Cu1Ce1 catalyst exhibited the best CO-SCR performance (about 100 %) in the widest temperature window (450–700 ℃). Notably, this catalyst still showed excellent stability in the presence of H2O and SO2. It was found that the appropriate molar ratio of Cu and Ce could optimize the pores of Cu-Ce catalysts, and increase their specific surface area. This could contribute to the contact between reaction gas and active sites. The stronger synergistic effect between Cu and Ce could be conducive to the increase of chemisorbed oxygen, and then enhance the redox properties. These might be the key factors for the improvement of 3DOM Cu1Ce1 catalytic activity. In addition, the molar ratio of Cu to Ce had a significant influence on the adsorption of CO, which might cause the difference in the consumption of active oxygen and the formation of oxygen vacancies, thus affecting the CO-SCR performance of 3DOM Cu-Ce catalysts.